Seat belt retractors typically have a spool on which seat belt webbing is wound and from which webbing may be unwound, for example, when a vehicle occupant extends the seat belt webbing around the occupant's body. In response to a vehicle crash condition, the spool is locked against unwinding so that the seat belt webbing will restrain the vehicle occupant in a vehicle seat. To enhance the performance of seat belt retractors over a range of occupant sizes or weights and over a range of vehicle crash conditions, mechanisms, such as torsion bars, have been added to seat belt retractors. It has also been proposed to have multiple torsion bars operably connected to a seat belt retractor and to engage the torsion bars selectively to limit the load applied to a vehicle occupant by the seat belt webbing in a vehicle crash.